Why do my 258418 boolits tumble?.

[PAT303]

I shot quite a few 258418 boolits yesterday fireforming some 25/303 cases and they all tumbled.The rifle is an M17 sporter with a 1-12 twist barrel and the load was 10grns of Trail Boss.Going by the greenhills formula I really need a 1-10 but a few people on here have shot this same boolit with the 1-12 with very good results so why don't mine work?.The rifle is very accurate with jacketed boolits and it has a very clean bore and the one boolit I found has very deep well defind rifling marks on it for 2/3rds of it's length.The bore is .257 and I polished the sizer to .257 and the alloy is WW cut with pistol range scrap and AC,they are soft so should I go harder and then bump up the speed?.Any help will be appreciated. Pat

[stubshaft]

Velocity is too low? One of my friends talked me into using TB in one of my 500 S&W's with a 400gr RCBS. I KNOW this boolit shoots well with normal charges. Anyway, to make a long story short. They left imprints in the target at 25yds that clearly showed the were tumbling.

[mooman76]

If your bore is in fact 257 you need to go with a bigger boolit than 257. Should be more like 258 or 259. Did you slug the bore to know it is in fact 257?

[MtGun44]

For .30 cal I use .002 to .003 larger than groove diam.

I think you have to small a boolit.

Bill

[runfiverun]

negative on the has to be bigger thing..

i shoot 358 in my 358 bbl'd 358 win at over 2200.
and 224 in my 223 rem with a 224 bbl at over 2700.
and...
just make them harder and go faster 1-10's will generally go 18-1900 with good accuracy.
a 1-12 will generally do 22-2300 and hold that same accuracy.

to sum it up waterdrop and go faster.

[koehn,jim]

In my opion the bullets are not traveling fast enough. I have a good load using 18 gr of 2400 and a 89grain loverlin from a grp buy on here. I am using them in a 25-06 and need the faster load to get what I want. I have tried 10 grains of red dot and 700x and got the tumbling you describe but the 2400 does not and is extremly accurate. I have that same bullet I am going to try tuesday at the range and will let you know.